1. Field of the Invention
Embodiments disclosed herein generally relate to a method and system for fluid injection. In particular, embodiments disclosed herein relate to a method and system for injecting viscous fluids, unweighted fluids, low-weighted fluids, and/or slurries in a downhole formation.
2. Background Art
In the drilling of wells, a drill bit is used to dig many thousands of feet into the earth's crust. Oil rigs typically employ a derrick that extends above the well drilling platform. The derrick supports joint after joint of drill pipe connected end-to-end during the drilling operation. As the drill bit is pushed further into the earth, additional pipe joints are added to the ever lengthening “string” or “drill string”. Therefore, the drill string includes a plurality of joints of pipe.
Fluid or “drilling mud” is pumped from the well drilling platform, through the drill string, and to a drill bit supported at the lower or distal end of the drill string. The drilling mud lubricates the drill bit and carries away well cuttings generated by the drill bit as it digs deeper. The cuttings are carried in a return flow stream of drilling mud through the well annulus and back to the well drilling platform at the earth's surface. When the drilling mud reaches the platform, it is contaminated with pieces of shale and rock that are known in the industry as well cuttings or drill cuttings. Once the drill cuttings, drilling mud, and other drilling effluents containing solid particles reach the platform, a solids control equipment that may include shale shakers, desanders, desilters, mud cleaners, and/or oilfield decanter centrifuges, is typically used to remove the drilling mud from the drill cuttings so that the drilling mud may be reused. The remaining drill cuttings, waste, and associated residual drilling fluids are then transferred to a holding trough for disposal. In some situations, for example with specific types of drilling fluids, the drilling fluid may not be reused and it must be disposed of. Typically, the non-recycled drilling fluid is disposed of separately from the drill cuttings and other waste by transporting the drilling fluid via a vessel to a disposal site.
The disposal of the drill cuttings and drilling mud is a complex environmental problem. Drill cuttings contain not only the residual drilling mud product that would contaminate the surrounding environment, but may also contain oil and other waste that is particularly hazardous to the environment, especially when drilling in a marine environment.
One method of disposing of oily-contaminated cuttings and other drill cutting waste is to re-inject the cuttings into the formation using a cuttings re-injection operation. Generally, the injection process involves the preparation of a slurry within surface-based equipment and pumping the slurry into a well that extends relatively deep underground into a receiving stratum or adequate formation.
In addition to re-injecting cuttings, it is often necessary to inject other types of fluids downhole during a variety of operations. For example, in some cases, it may be necessary to increase the permeability of a formation into which waste is injected. One method for increasing formation permeability known in the art is hydraulic fracturing, wherein a fluid is forced into the formation to create fractures that extend into the formation from the borehole. In another application, well cleaning or treatment fluids may be forced into a wellbore during regular maintenance or well rehabilitation.
Due to the limited space, it is common to modularize operations and to swap out modules when not needed or when space is needed for the equipment. For example, with respect to cuttings re-injection operations, cuttings containers may be offloaded from the rig to make room for modularized equipment used for slurrification. These lifting operations, as mentioned above, are difficult, dangerous, and expensive. Additionally, many of these modularized operations include redundant equipment, such as pumps, valves, and tanks or storage vessels.
Accordingly, there exists a need for more efficient methods of injecting a fluid, or a fluid and a slurry, downhole that require optimized use of rig deck space.